Challenges in the Microbiological Diagnosis of Implant-Associated Infections: A Summary of the Current Knowledge

Implant-associated infections are characterized by microbial biofilm formation on implant surface, which renders the microbiological diagnosis challenging and requires, in the majority of cases, a complete device removal along with a prolonged antimicrobial therapy. Traditional cultures have shown unsatisfactory sensitivity and a significant advance in the field has been represented by both the application of the sonication technique for the detachment of live bacteria from biofilm and the implementation of metabolic and molecular assays. However, despite the recent progresses in the microbiological diagnosis have considerably reduced the rate of culture-negative infections, still their reported incidence is not negligible. Overall, several culture- and non-culture based methods have been developed for diagnosis optimization, which mostly relies on pre-operative and intra-operative (i.e., removed implants and surrounding tissues) samples. This review outlines the principal culture- and non-culture based methods for the diagnosis of the causative agents of implant-associated infections and gives an overview on their application in the clinical practice. Furthermore, advantages and disadvantages of each method are described.

Formulation and Toxicity Evaluation of Nanostructured Lipid Carriers for the Treatment of Acne

Background: Acne vulgarise is an inflammatory disease involving the pathological alteration of the sebaceous glands of the body. It is not a life-threatening disease but has a great influence on lifestyle. Topical combination therapy of vitamin A and antibacterial drugs is an effective treatment for acne. Materials and Methods: The current work investigates the nanostructure lipid colloidal carrier system of Tretinoin and Clindamycin phosphate. Nanostructured lipid carriers (NLCs) were prepared by highspeed homogenization-sonication technique and characterized for physicochemical properties, permeation, in vivo anti-acne and toxicity (acute 2000 mg/Kg, repeat 1000 mg/kg) in Wistar rats. Results: The prepared system was found to be stable, homogenous with more site retention of drugs having non-irritation and toxicity potential. The formulation showed a size of 283 nm, polydispersity index (PDI) 0.43 and Zeta potential (ZP) -37.9 mV with drug entrapment 92.0% and 66.15% for tretinoin and clindamycin respectively. Observed permeation was 18 % and 45% for Tretinoin and Clindamycin less than marketed formulation which is more focused on dermal retention of drug. No significant abnormalities and toxicological symptoms were observed for acute and repeat dose toxicity study for histopathology and haematological examinations of organs. Conclusion: Prepared NLC formulation was aimed at epidermal targeting. Based on obtained results it is concluded that developed lipid-based nanocarrier system of selected drugs showed the targeting potential for effective acne treatment.

INTERFACIAL PROPERTIES OF HYBRID CELLULOSE NANOCRYSTAL/CARBONACEOUS NANOMATERIAL COMPOSITES

Cellulose nanocrystal (CNCs) assisted carbon nanotubes (CNTs) and graphene nanoplatelets (GnP) were used to modify the interfacial region of carbon fiber (CF) and polymer matrix to strengthen the properties of carbon fiber-reinforced polymer (CFRP). Before transferring CNC-CNTs and CNC-GnPs on the CF surface by an immersion coating method, the nanomaterials were dispersed in DI water homogeneously by using probe sonication technique without additives. The results showed that the addition of CNC-CNT and CNC-GnP adjusted the interfacial chemistry of CFRP with the formation of polar groups. Furthermore, according to the single fiber fragmentation test (SFFT), the interfacial shear strength (IFSS) of CNC-GnP 6:1 and CNC-CNT 10:1 added CFRP increased to 55 MPa and 64 MPa due to modified interfacial chemistry by the incorporation of the nanomaterials. This processing technique also resulted in improvement in interlaminar shear strength (ILSS) in CFRPs from 35 MPa (neat composite) to 45 (CNC-GnP 6:1) MPa and 52 MPa (CNC-CNT 10:1).

Synthesis and Characterisations of Reduced Graphene Oxide Prepared by Microwave Irradiation with Sonication

Recently, reducing graphene oxide (GO) through microwave irradiation has been extensively explored in order to scale up the mass production of graphene. We report the simple technique to reduce GO by means of microwave irradiation combined with a sonication technique. The microwave-reduced GO (MWrGO) is formed by exposing a microwave onto GO powder in order to reduce the oxygen functional group and then followed by exfoliating via a sonication method. The time exposure of the microwave irradiation was 20 min with the powers of 450 W and 800 W. The UV-visible (UV-vis) spectra showed the evolution of GO into MWrGO indicated by the red shift of the absorption peak from 230 nm to 267 nm and disappearance of the shouldering peak at 300 nm. The reduction of the oxygen functional group has been proved by Fourier transform infrared (FTIR) spectra. Furthermore, the scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) data demonstrated further confirmation of the reduction of GO and the formation of basal planes of sp2 carbon clusters of the sample due to the treatment. The EDS spectra revealed that the MWrGO by 800-W-irradiation had much less oxygen functional groups and much more carbon content than GO. The proposed synthesis method is simple and readily controlled for a mass production of graphene from GO.

Development of Apigenin-Loaded Niosomes Using Ecological Probe Sonication Technique for enhanced oral delivery: Application of Box-Behnken Design

Background: Apigenin (APG), a natural bioactive flavonoid, has multiple pharmacological effects. However, its poor aqueous solubility hinders its clinical benefits. Objective and Methods: The work aimed to develop novel apigenin-loaded niosomes (APG-NIO) with ecological probe sonication techniques. The formulation was statistically optimized by Box-Behnken design (BBD), and the independent variables were selected as Span 80 (X1), Poloxamer 188 (X2), and Tween 80 (X3) at three levels, and the dependent variables were identified as: particle size (Y1), polydispersity index (Y2), and % entrapment efficiency (Y3). The formulation was characterized for various parameters such as vesicle shape, size, PDI, %EE, solubility, in vitro drug release, and antioxidant potential. Results: The optimized APG-NIO formulation was found to have a spherical shape with homogenous distribution and a low polydispersity index. It has a particle size of 425.77 nm, zeta potential -17.1±0.9 mV, and %EE of 89.63. The aqueous solubility of APG-NIO was found approximately 45 times higher than that of pure APG. The formulation showed a higher drug release rate as compared to pure APG in phosphate buffer pH 7.4 and followed the Higuchi release model with a non-Fickian transport mechanism. The stability was found at 4°C for 3 months. The antioxidant potential of APG-NIO was significantly increased in comparison to the pure drug suspension in the DPPH• assay. Conclusion: These findings suggest that the probe sonication technique is an alternative, cost-effective, simple, and green method for the development of niosomes, and BBD is a useful optimization tool for identifying the effect of formulation variables.

‘Preparation and characterization of a novel mucoadhesive carvedilol nano-sponge: a promising platform for buccal antihypertensive delivery’

Purpose: Carvedilol (CRV) is a non-selective beta-blocker used for hypertension treatment, angina pectoris, and heart failure. Oral administration of CRV showed poor bioavailability (25%), which may be due to exposure to the first-pass metabolism. Buccal delivery was used to boost its bioavailability.Methods: In this study carboxymethylcellulose/hydroxypropyl cellulose (CMC/HPC) composite buccal sponge enriched with CRV bilosomes was developed. Bilosomes were prepared using the thin-film hydration-sonication technique by applying a 32 -factorial design.Results: BL9 possessed the highest desirability value (0.861) and therefore, it was chosen as an optimal bilosomes. It exhibited a spherical shape with 217.2 nm, 87.13% entrapment efficiency, and a sustained release of CRV up to 24h. Consecutively, BL9 was incorporated in a CMC/HPC gel and lyophilized for 24 h to obtain a CMC-HPCL9 bilosomal sponge to enhance CRV buccal delivery. Morphological analysis of the prepared sponge with improved swelling showed a porosity of 67.58 percent. The in vivo assessment of rats indicates that the CMC-HPC/BL9 sponge enhances systolic/diastolic blood pressure, lipid profiles, oxidative stress biomarkers, and heart biomarkers with improved heart tissue quality.Conclusion: These results strongly encourage the use of this novel CMC-HPC/BL9 composite buccal sponge for the management of hypertension.

Electrical Conductivity of PA6/Graphite and Graphite Nanoplatelets Composites using Two Processing Streams

The percolation threshold (PT) of any polymer/particulate carbon composite depends on the processing, the dispersed state of the filler, the matrix used and the morphology attained. Sonication technique was used to make PA6/G and PA6/GNP composites employing in situ polymerisation, after which their electrical conductivity behaviours were investigated. While overhead stirring and horn sonication were used to distribute and disperse the carbon fillers, the composites were made in 2 streams 40/10 and 20/20. The 40/10 stream implies that while dispersing the carbon fillers in PA6 monomer, 40% amplitude of sonication was applied for 10 minutes whereas the 20/20 stream implies 20% amplitude of sonication for 20 minutes. In both streams, the dispersing strain imparted on the monomer/carbon mixture was 400 in magnitude. Purely ohmic electrical conductivity behaviour was attained at 9.75 G wt. % for IG 40/10 system. For composites in the IG 20/20 system, same was attained at 10.00 G wt. %. Electrical conductivity sufficient for electrostatic discharge applications was achieved above 15 G wt. % in the IG 40/10 system. Using the power law percolation theory, percolation threshold was attained at 9.7 G wt. % loading in IG 40/10 system, while same was attained at 7.6 G wt. % loading in IG 20/20 system. For the GNP based systems, percolation threshold occurred at 5.2 GNP wt. % in the INP 40/10 system whereas same occurred at 7.4 GNP wt. % in the IG 20/20 system.

Far-Infrared Emission Properties and Thermogravimetric Analysis of Ceramic-Embedded Polyurethane Films

The far-infrared ray (FIR) is one kind of electromagnetic wave employed for numerous bio-interactive applications such as body thermoregulation, infrared therapy, etc. Tuning the FIR-emitting property of the functional textile surface can initiate a new horizon to utilize this property in sportswear or even smart textiles. Ceramic particles were studied for their unique ability to constantly emit FIR rays. The purpose of this research is to characterize the FIR emission properties and the thermogravimetric analysis of ceramic-embedded polyurethane films. For this purpose, ceramic particles such as aluminum oxide, silicon dioxide, and titanium dioxide were incorporated (individually) with water-based polyurethane (WPU) binder by a sonication technique to make a thin layer of film. Significant improvement in FIR emissive property of the films was found when using different ceramic particles into the polyurethane films. Reflection and transmission at the FIR range were measured with a gold integrating sphere by Fourier-transform infrared (FTIR) spectrometer. The samples were also characterized by thermogravimetric analysis (TGA). Different physical tests, such as tensile strength and contact angle measurements, were performed to illustrate the mechanical properties of the films. The study suggested that the mechanical properties of the polyurethane films were significantly influenced by the addition of ceramic particles.

Micro-Ribbons and Micro-Wires Silica Synthesis Using Bottom-Top Technique

Silica is one of the most important materials used in many industries. The basic factor on which the selection process depends is the structural form, which is dependent on the various physical and chemical properties. One of the common methods in preparing pure silica is that it needs more than one stage to ensure the preparation process completion. The goal of this research is studying the nucleation technique (Bottom-top) for micro-wires and micro-ribbons silica synthesis. The silica nanoand microstructures are prepared using a duality (one step); a combination of alkali chemical etching process {potassium hydroxide (3 wt %) and n-propanol (30 Vol %)} and the ultra-sonication technique. In addition, the used materials in the preparation process are environmentally friendly materials that produce no harmful residues. The powder product is characterized using XRD, FTIR, Raman spectrum and SEM for determining the shape of architectures. The most significant factor of the nucleation mechanism is the sonication time of silica powder production during the dual technique. The product stages are as follows; silica nanoparticles (21-38 nm), nanoclusters silica (46 – 67 nm), micro-wires silica (1.17 – 6.29 μm), and micro-ribbons silica (19.4 – 54.1 μm). It's allowing for use in environmental applications (multiple wastewater purification, multiple uses in air filters, as well as many industrial applications).